Method of treating well fluids



1 6, 1953 w. c. CARLISLE ET AL 2,654,436

METHOD OF TREATING WELL FLUIDS Filed July 16, 1951 2 Sheets-Sheet l W////& C. Car/w/e do/m H. Mc Carvel/ INVENTORJ BY ham A TTORNEY Oct. 6, 1953 w. c. CARLISLE ET AL METHOD OF TREATING WELL FLUIDS 2 Sheets-Sheet 2 Filed July 16, 1951 Wl///J C. Car/m/e John H. Mc Carve INVENTORS Patented Oct. 6, 1953 UNITED STATES PATENT OFFICE METHOD OF TREATING WELL FLUIDS Application July 16, 1951, Serial No. 236,922

2 Claims. (01466-21) 1 This invention relates to a method for inhibiting corrosion in well tubing by adding chemical inhibitor to well fluids.

In the past, one of the most serious problems in the oil industry has been the corrosion of tubing, rods, pump parts, wellhead fittings and flow lines of oil Wells producing fluids containing hydrogen sulfide. This corrosion problem has been particularly prevalent in the sour crude areas of West Texas. In an effort to overcome this corrosion problem, chemical inhibitors have come into general use recently.

Much difficulty has been experienced in the development of the proper types of chemical inhibitors, but today there are available numerous inhibitors which are suitable for most purposes. These inhibitors are preferably a free flowing liquid or an easily dissolved solid, and this invention contemplates the use of any of the known inhibitors which are capable of being pumped.

It has been found in the use of the chemical inhibitors in oil Wells that loss of the inhibitor during pumping operations has become excessive at times when the inhibitor is fed into the well tubing by the known methods and apparatus. This excessive loss has been primarily due to the inhibitors being sucked into the tubing from the annulus thereabout whenever a low pressure condition occurred in the tubing due to surges of well gases.

It is, therefore, an object of this invention to provide a method for injecting chemical inhibitor into an oil well tubing.

It is a further object of this invention to provide a method for injecting a chemical inhibitor into a tubing without excessive losses of the chemical inhibitor into the tubing upon the occurrence of a low pressure condition therein.

Another object of this invention is to provide a method for injecting a chemical inhibitor whereby the quantity of the inhibitor fed into the well tubing will be substantially the same as the quantity of the inhibitor pumped at the surface, the feeding into the tubing being simultaneous with the pumping.

In the practice of our invention we provide an injection pump for injecting a chemical inhibitor into an annulus about a well tubing down to a packer in the annulus and admitting the inhibitor through a valve means so that the quantity of inhibitor fed into the well tubing through the valve means will be substantially the same as the quantity of inhibitor pumped by the injection pump, regardless of the head of inhibitor presentin the annulus.

Other and additional objects of this invention will be readily apparent when the following description is considered in connection with the ac-- companying drawings, wherein:

Fig. 1 is a section illustrating the complete apparatus assembly used in carrying out the method of this invention.

Fig. 2 is a section of the upperportion of the valve means used in this invention.

Fig. 2-A is a section showing the lower portion of the valve means used in this invention.

Following is a, detailed description of the method and apparatus of this invention wherein like numerals are used to indicate like parts in all views of the drawings.

The method can best be understood by referring to Fig. 1 of the drawings. Therein is shown a casing 5 inserted into the well bore and having Openings 6 in the casing, which are positioned in alignment with an oil bearing strata. At the top of the casing 5 above the ground level, may be positioned the Christmas tree structure 8. As is well known, this Christmas tree structure 8 includes many valves and other fittings. In this invention, the Christmas tree 8 has in particular thereon a valve II! which is for the outlet of the oil and other fluids produced from the well. Below the valve II! is positioned a pump [2 which i generally of the positive displacement type or proportioning type. It will be noted that within the casing 5 is positioned the tubing l5, which tubing is of the type generally used in oil well production. This tubing l5 extends down to the oil bearing strata l6 and at the end thereof may be located a strainer 20, which is commonly used toprevent'the entrance of large particles of sand and other material. The upper end of the tubing I5 is arranged so that the fluids will flow therethrough and into the section of pipe controlled by the valve l0. Separating the tubing [5 and the casing 5 is an annulus 22. At the bottom of the tubing l5 just above the screen 20 is positioned packing elements or packers 25. Thus, these packers 25 determine the height of the annular space 22. Near the bottom of the annulus 22 and above the packers 25, the valve means 26- is located. This valve means 26 is connected to the tubing I5 and there is an appropriate openmg 28 best seen in Fig. 2 for the admittance of fluids through the valve means 26 and into the tubing l5. To correspond with the opening 28, there is an opening 29 in the valve head 30. This valve head- 30 is generally welded to the tubing l5. Threads 32 are provided on the valve head 30 to provide for insertion therein of threads 33 on the check valve body 36. The check valve proper 35 is the subject matter of our co-pending application, Serial Number 219,808, filed April '7, 1951.

It should be particularly noted that this novel check valve 35 has a hollow plunger member 38 which has thereon the valve tip 40 which engages with the valve ring 4|, valve washer 42., and valve seat 4 3. Thus, there is provided a combination metal and resilient material seat. The washer 42 may be made of rubber or synthetic materials such as Hycar. The spring, 45 urges the hollow plunger member 38 into contact with the valve seat 43. This type of seat which has the combination metal and resilient material is not as susceptible to wire-drawing or wearing action as is a plain metal seat. Eurthermore, by using the hollow plunger member 38, the maximum flow of fluids through the check valve is obtained during the time the valve is in open position. 7

Below the check. valve :35 positioned atfl'ow valve 50 which flow valve '50. a valve member 52 which is urged into. contact with the valve seat 53 by means of a spring 55. The tension of the spring may be adjusted by means of the screw 58. The fluid passes through this flow valve by passing through the opening 50 in the valve member 52. Below the flow valve 50 may be another valve 59 which is .of similar construction to the flow valve 50 but generally has provided a much weaker spring 62 than the spring 55-. In fact, any series of flow valves such as 50 and 59 may be used in the combination desired for the best operation; but it has been found desirable to have at least these two flow valves used in conjunction with each. other. The. additional flow valve 59, inthe first place, provides an additional valve for checking the flow of fluids from the tubing in the event. that the upper flow valve 50 and the check valve 25 fail to hold. the pressure. Further, the lower flow valve :59", by being :set a lower pressure, will open before the valve 50, and thereby eliminate some of the wear on the upper flow valve 50 by causing the upper flow valve 50 to open with a snapping action rather than with a slow, Wearing type of action. Thus the flow valve 50 will normally be set to carry the full load as will be more fully explained hereinafter. It willbe observed that the adjusting screw is to screw 58, and valve member (i3 is similar to valve member 52. Valve member .63 engages on, seat 64 as shown in Fig. 2-,A. Passages 6.7 are provided in the valve member 63.

Immediately below the flow valve 59, or any other flow valve which may be desirable to use, it is preferable to inserta screen 65. which pre vents the flow of damaging particles through the valve assembly 2-6. It is to be understood that various sizes of openings 66 may be used in the strainer 55 in order to obtain the maximum. efliciency commensurate with the prevention of particles from entering the valve means 26.

In order to prevent damage to the valve means 216 when raising and lowering the tubing, it has been found desirable to weld or otherwise aflix to the tubing [5 a projecting flange 68 which extends somewhat beyond thev extremity of the valve means 2.6 so that the valve means 26 will not touch the side of the casing and, thereby, damage to the valve means 26 will be prevented.

In carrying out the methods of this invention, the, corrosion inhibitors may be any of the fluids now used as chemical corrosion inhibitors now on- 4 the market. It has been found that by providing the packers 25 at the bottom of the annular space 22 that the resulting head of chemical corrosion inhibitor will normally tend to flow into the well tubing I 5 unless suitable means are provided for preventing such ingress. The valve means 26 provides the structure for preventing such ingress. When the pump 12 is operated, a predetermined portion of chemical corrosion inhibitor is pumped into the annulus 22 and this, in turn, will enter the tubing l5 through the valve means 26.. Thus, if one quart of liquid is pumped by the pump l2, the valve means 26 is so regulated that one quart only of liquid will be forced through the valve means 26 into the well tubing. It is necessary to overcome the pressure in the tubing in order to inject into the tubing I 5 the corrosion inhibitor which is present in the annulus 22; so, normally, the valve means 26 has been set to open at the most prevalent pressure found in the well area.

0i course, it must :be appreciated that the headof fluids in the annulus 22 will also contribute torthe pressure so that the head plus the pres- Sure exerted by the pump l2 will be the total pressure exerted against the valve means 26, and thus, the valve means 26 must be set to open when that total pressure just exceeds the total pressure in the tubing at the depth of the valve means 26 on the tubing [5. As previously mentioned, the spring 55 in the flow valve 50 is generally of sufiicient strength and set so that it will not open until the total pressure from the pump 1.2 and the annulus 22 is greater than the pressure Within the tubing 15. The flow valve 59 may or may not be used, but. it is preferably used, and. serves, primarily, as an auxiliary valve with a very low load rate so that it will normally be open when the pressure slightly exceeds the head pressure. in the annulus 2.2.. Thus, the flow valve 59 will serve to-prevent jiggling of the valve member 52 because .of small pressure variations, and so increase the wear life of the flow valve 50. It can be seen that when a predetermined amount of corrosion inhibitor is pumped with the positive displacement pump E2, the same quantity must necessarily enter the valve means 26, because the annulus 22 is normally kept full.

Oneof the main problems which has been overcome by the use of the method of this invention has been the loss of corrosion inhibitor fluids into the tubing 15 when low pressures occur within the tubing I5 by reason of :gas surges from, the .oilbearing strata IS. The flow valves 50 and 5.9 serve to prevent the. corrosion inhibitor fluid from entering the tubing [5 until there is a total pressure on the valve 50 which is in excess of normal total pressure in the tubing l5.

Also, the well fluids that come up through the tubing 45 will ,not be able to pass through the valve means 25 and damage it, or force the chemical inhibitor out of the annulus '22 because of the. check valve 35 which is positioned at the top of the valve assembly 26.. This check valve, as has been previously pointed out, has a resilient rubber washer or gasket 42 and a metal seat 43 which serves to give long life and prevent wearing due to wire-drawing effects. The flow valves 50 and 59 additionally serve as check valves, but, f ur e, h y, having metal to metal seat con tacts, do not havev the advantage of the check valve 35.. It is believed readily apparent from the description of this invention that a method and apparatus has :been invented which enables the feeding of a predetermined quantity of chemical inhibitor into the well fluid passing through the well tubing, and also enabling the discontinuance of the feeding of the chemical inhibitor into the well fluid when desired without danger of loss of the corrosion inhibitor into the fluids during surges of low pressures.

Broadly, this invention contemplates the method of injecting corrosion inhibiting fluid into a well tubing in a predetermined amount which is controllable by the operator.

What is claimed is:

1. A method of preventing corrosion in a well comprising the steps of introducing a column of a corrosion inhibiting chemical into an annular passage between a well tubing and a well casing, continuing the introducing until said column is of a length substantially equal to the length of the well tubing, thereafter pumping into said column an additional quantity of chemical, and forcing said additional quantity into said well tubing near the bottom of said column of chemical against the pressure in said well tubing.

2. A method of preventing corrosion in a well comprising the steps of introducing a column of a corrosion inhibiting chemical into an annular a passage between a well tubing and a well casing, continuing the introducing until said column is of a length substantially equal to-the length of the well tubing, thereafter pumping, into said column an additional quantity of chemical, forcing said additional quantity into said well tubing near the bottom of said column of chemical against the pressure in said well tubing, ceasing to pump said chemical, and simultaneously discontinuing the introducing of said corrosion inhibiting chemical into said tubing.

WILLIS c. CARLISLE. JOHN H. McCARVELL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,703,423 Herman Feb. 26, 1929 2,143,251 Savitz .Jan. 10, 1939 2,144,144 Crickmer Jan. 17, 1939 2,307,662 Baylor Jan. 5, 1943 2,357,559 Smith Sept. 5, 1944 2,581,540 Kennedy et a1. Jan. 8, 1952 

1. A METHOD OF PREVENTING CORROSION IN A WELL COMPRISING THE STEPS OF INTRODUCING A COLUMN OF A CORROSION INHIBITING CHEMICAL INTO AN ANNULAR PASSAGE BETWEEN A WELL TUBING AND A WELL CASING, 